如何从python下载中排除404个页面

import urllib.request

def page_exists(url):
    try:
        response = urllib.request.urlopen(url)
        return True
    except urllib.error.HTTPError as e:
        if e.code == 404:  # 页面不存在，返回False
            return False
        else:  # 其他HTTP错误，抛出异常
            raise e

def exclude_404_pages(urls):
    valid_urls = []  # 存储有效的URL
    for url in urls:
        if page_exists(url):
            valid_urls.append(url)
    return valid_urls

urls = ["https://example.com/page1", "https://example.com/page2", "https://example.com/page404"]
valid_urls = exclude_404_pages(urls)
print(valid_urls)